This invention relates to a Liquid Crystal Displays (LCD) assembly in portable computing devices and electronic specialty products where the user can define the visible regions of an LCD display. More specifically, this invention relates to an LCD display where multiple polarizers define visible regions of a portable computer display to preserve computing privacy or provide a means on electronic novelties to amuse or educate a user via selective display of an answer or acknowledgement. The LCD configurable polarized region may also serve to gain access to or to facilitate usage of the electronic device.
Liquid crystal displays are a common display means on a large variety of portable computing devices and electronic novelty products. They are the display means of choice because of their power efficiency and high contrast characteristics. The images displayed on liquid crystal devices can be alphanumeric, graphic, pictorial, or video in nature. Liquid crystal displays are actually light valves that utilize cross polarization to effectively transmit or block light. To accomplish the graphic, alphanumeric, pictorial, or video display of information, a majority of common LCD systems are configured with two fixed polarizers sandwiching two glass plates with embedded electrodes that confine a mesomorphic material. Certain mesomorphic material (liquid crystals) have two useful properties. Light passing through the crystalline material rotates its plane of polarization, and mesomorphic crystals will freely align themselves to an electric field. When the crystals are illuminated by a polarized light source and aligned by an electric field, the change in light polarization over the aligned crystalline region is uniform, and can be cross-polarized to impede transmission of light. When the electric field is removed, the crystalline alignment is random and light polarization becomes effectively scattered, allowing transmission of light. There are three functional classifications of LCDs: reflective(watches without a backlight), transmissive (LCD projection) and transflective (laptop computers) which allow use of ambient light or backlighting. All three require one polarizer to polarize incident light, the liquid crystal to scatter or rotate the polarized light, and another polarizer to cross-polarize (block) all light rotated by the aligned liquid crystal. The cross polarizer can be located proximal to the display or remotely by the user. U.S. Pat. No. 4,859,994 issued to Zola et al. discloses a closed caption movie subtitle system where the LCD assembly comprises one fixed polarizer and the liquid crystal assembly. Audience members that required closed captioning would wear glasses correctly polarized and see a changing display beneath the movie screen. The rest of the audience would not be distracted by the constant messaging. In this embodiment the LCD always requires a set of glasses for remote cross-polarization to read the screen and viewing is absolute, where the user sees the entire display or nothing.
In portable computing devices such as laptop computers, the user frequently is in a public place such as an airport or on an airplane. The majority of these computing devices are carried for business purposes, and the nature of the work is proprietary. The screens normally display 20-30 lines of text while working on a word processing document. As the last line on the screen is typed, the entire text scrolls upward one line at a time. For added confidentiality, the users may display only the text line that they are currently writing and hide the rest of the document. For ultimate security, the users may wish to make the entire screen blank and use remote cross-polarized glasses so only they can see the text on the screen. Another portable computing application uses the new personal digital assistant technology such as the Apple Newton, made by Apple Computer Inc., Cupertino, Calif., A salesman may partition a portion of the screen where the customer sees retail prices and warranty information, and the salesman using cross-polarized glasses can see cost, inventory levels, and sales tips on the rest of the screen. He may repartition the screen for full viewing by the customers so they can answer a survey or any other function.
Some electronic novelties such as databanks are commonly used as dictionaries, language translators, and telephone address books. Many contain multi-line displays learning tools. When using these as reference tools, the user would configure the screen for complete viewing. However in a flash card mode, only the first line of the screen would be visible until the users would want to confirm their guess. The first line would contain a phrase to translate, a word to be defined, or a math problem. After guessing, they could make the consecutive lines visible by changing the cross-polarized region and determine the validity of their answer. The same configuration can be used for electronic novelties that ask trivia questions, or provide amusement by encrypting or disguising some puzzle or game.
LCD projection technology such as video projectors could have user defined cross-polarized regions to allow complete viewing, partial viewing, or selective viewing. On airplanes, inflight entertainment is provided using projection video. The system is employed for FAA safety instructions to all passengers at the beginning of the flight. Later for paid entertainment, headsets for audio are purchased to enjoy the feature film. The stewardess could set the cross-polarized region to display the entire screen for safety instructions. Later the screen can be set so the entire cabin views the top 10% of the screen, where the flight crew can display relevant text messages to the entire planeload of passengers. The lower 90% of the screen would contain the feature film, where passengers interested in entertainment can purchase cross-polarized glasses to view it. The remainder of the passengers wouldn't be disturbed by the video only portion of the film.
It can be seen that by creating a user-defined, cross-polarized region of an LCD display, electronic devices incorporating such a display can be made to provide computing privacy, accessibility to the device, strategic information separation, and information separation to multiple users.